python queue.priority queue code example
Example 1: queue python
from queue import Queue
q = Queue()
q.size() # returns the current lenght of queue
q.empty() # returns True if empty, False otherwise
q.put(item)
q.get()
Example 2: python threading queue
import threading, queue
q = queue.Queue()
def worker():
while True:
item = q.get()
print(f'Working on {item}')
print(f'Finished {item}')
q.task_done()
# turn-on the worker thread
threading.Thread(target=worker, daemon=True).start()
# send thirty task requests to the worker
for item in range(30):
q.put(item)
print('All task requests sent\n', end='')
# block until all tasks are done
q.join()
print('All work completed')
Example 3: python queue.priority queue
from queue import PriorityQueue
class PqElement(object):
def __init__(self, value: int):
self.val = value
#Custom Compare Function (less than or equsal)
def __lt__(self, other):
"""self < obj."""
return self.val > other.val
#Print each element function
def __repr__(self):
return f'PQE:{self.val}'
#Usage-
pq = PriorityQueue()
pq.put(PqElement(v)) #Add Item - O(Log(n))
topValue = pq.get() #Pop top item - O(1)
topValue = pq.queue[0].val #Get top value - O(1)